Hi Elliot,
The following paper might get you part of the way, though with a somewhat different sort of method:
Article title
Detecting Brain Activation in FMRI Data without Prior Knowledge of Mental Event Timing
Author
Levin, D. N. Uftring, S. J.
Journal title
NEUROIMAGE
Bibliographic details 2001, VOL 13; PART 1, pages 153-160